Multiple piston type pump or motor



Sept. 7, 1965 B. H MOSBACHER MULTIPLE PISTON TYPE PUMP OR MOTOR 2Sheets-Sheet 1 Filed Oct. 31, 1962 P 1965 B. H MOSBACHER 3,204,572

MULTIPLE PISTON TYPE PUMP OR MOTOR Filed Oct. 31, 1962 2 Sheets-Sheet 2CD 404 [Q lo 7 i I 405 q: 1 )//8 United States Patent 3,204,572 MULTKPLEPISTUN TYPE PUMP 0R MOTOR Bruce H. Mosbacher, Rockford, lll., assignorto Roper Hydraulics, Inc., Commerce, Ga., a corporation of Georgia FiledOct. 31, 1962, Ser. No. 234,386 9 (Ilairns. (Cl. 103174) This inventionrelates to a multiple piston type pump or motor device.

An important object of this invention is to provide a multiple pistontype pump adapted to provide either plural separate discharges forsupplying proportional flows to several outlets or to provide combinedflows from several or all of the piston pumping units.

It is an important object of this invention to provide an improvedmultiple piston pumping apparatus adapted to provide plural segregatedflows or combined flows from several or all of the pumping units, andwhich pumping apparatus is of simple and economical construction.

Another object of this invention is to provide an improved multiplepiston type pump or motor wherein the pistons are mounted on the pumpcasing and the cylinders are formed in a member which is moved inorbital fashion relative to the casing and pistons to effect cyclicreciprocation of the pistons in the cylinders and to also valve theflows of fluid to and from the pump cylinders in proper timed relationto the reciprocation of the pistons.

A more particular object of this invention is to provide a multiplepiston type pump or motor of the type wherein the pump cylinders areformed in a cylinder member which is moved in orbital fashion in a pumpcasing by an eccentric, and which pump or motor has an improvedarrangement for mounting the piston members on the casing to hold thepiston members against axial shifting while permitting limited crosswiseoscillation of the piston members during rotation of the eccentric.

These, together with various ancillary objects and advantages of thisinvention will be more readily appreciated as the same becomes betterunderstood by reference to the following detailed description when takenin connection with the accompanying drawings wherein:

FIG. 1 is a longitudinal sectional view through the pumping apparatus;

FIG. 2 is a transverse sectional view taken on the plane 22 of FIG. 1;

FIG. 3 is an enlarged fragmentary sectional view taken on the plane 2-2of FIG. 1;

FIG. 4 is a transverse sectional view taken on the plane 44 of FIG. 1and illustrating one of the port plates;

FIG. 5 is a transverse sectional view taken on the plane 5-5 of FIG. 1and illustrating the other of the port plates; and

FIG. 6 is a fragmentary end view of the pumping apparatus illustrating amanifold arrangement for interconnecting several of the pump outlets.

The apparatus of the present invention is adapted for use as a pump ormotor. For convenience, the apparatus is hereinafter described as afiuid piunp, it being understood that it can also be operated as a motorif fluid under pressure is supplied thereto.

The pumping apparatus in general includes a casing 10 defining a cavity11, a cylinder member 12 disposed in the cavity and connected to aneccentric 13 on a shaft 14, a plurality of piston members 15, and ameans 16 for mounting the piston members on the pump casing. Thecylinder member 12 is moved in orbital fashion in the pump cavity toeffect cyclic reciprocation of the pistons 15, and the cylinder member12 has valve ports therein which cooperate with inlet and dischargeports in the casing to valve the flows of fluid to and from the pumpcylinders in proper timed relation with the reciprocation of thepistons.

The casing is advantageously arranged to enable stacking of two or morepumping units, if desired. For this purpose, the pump casing is formedwith an annular casing member 21 having port plates 22 and 23 attachedto opposite sides and sealed thereto as by O-rings 24 to form a casingunit. One such casing unit can be employed, or several of such casingunits can be stacked. End plates 26 and 27 are provided at oppositesides of the single or multiple casing unit assembly, and the severalparts are retained in assembled relation as by fasteners 28. The portplates 22 and 23 have generally fiat side faces 31 and 32 at oppositesides of the cavity and the cylinder member 12 has end faces 33 and 34disposed in rubbing engagement with the side faces 31 and 32. Thecylinder member has an axial bore 36 and a plurality of cylinder bores37 extending generally radially of the annular cylinder member. As shownherein, twelve cylinder bores are provided, it being understood that agreater or lesser number of cylinder bores could be provided if desired.The cylinder bores 37 are conveniently arranged to intersect the axialbore 36 and the cylinder member is rotatably supported on the eccentric13 by a steel backed bushing 39 which is pressed into the bore 36 in thecylinder member to also close the inner ends of the cylinder bores 37.Plugs such as 49 are preferably provided in the inner ends of thecylinder bores to limit the dead space in the cylinders and to avoidforming an air or gas trap in the cylinder bores. The shaft 14 isrotatably supported in bushings 41 and 42 in the port plates and has akeyed end which is connected through an Oldham type coupling 44 to astub drive shaft 45. In the form shown, this drive shaft is rotatablysupported in bearings 46 on the end member 26 and a shaft seal 47 isprovided for sealing the interface between the stub shaft and the pumpcasing.

The piston members 15 are herein shown in the form of generallycylindrical pins which reciprocate in the cylinder bores 37 as theeccentric 13 rotates and moves the cylinder member in orbital fashion inthe cavity. In accordance with the present invention, the piston membersare mounted on the casing in such a manner as to constrain the pistonmembers against axial reciprocation relative to the casing whilepermitting oscillation of the piston members in a directioncircumferentially of the shaft during orbital movement of the cylindermember. For this purpose, the annular casing member 21 is formed with aplurality of notches 51 on the inner periphery thereof which definecircumferentially spaced stop faces 51a and 51b. The cylinder member 12will shift circumferentially of the shaft 14 a distance equal to twicethe eccentricity of the eccentric 13, and designated E in FIG. 3. Thestop faces 51a and 5111 are accordingly spaced apart a distancedesignated W in FIG. 3 and which is substantially equal to thecircumferential width of the piston member 15 at the point of contactwith the stop faces, plus twice the eccentricity E of the eccentric. Thepiston members can, accordingly, shift circumferentially from their midposition shown in FIG. 3, in either direction, a distance correspondingto the eccentricity of the cam to allow the cylinder member to oscillateduring rotation of the eccentric cam. With this arrangement, one pair ofdiametrically opposed piston members will engage relatively oppositestop faces 51a and 51b at substantially all times to prevent rotation ofthe cylinder member and to control the oscillation of the cylindermember 12 during rotation of the eccentric. As best shown in FIG. 2, thepiston members 15 which are disposed substantially perpendicular to theplane through the axes of the eccentric 14 and shaft 13, engagerelatively opposite stop faces 51a and 51b. The other piston members arespaced varied distances from their respective stop faces. However, asthe eccentric rotates, for example in a clockwise direction as viewed inFIG. 2, the next piston members in a clockwise direction from theaforementioned piston members move into engagement with the opposed stopfaces 51a and 51b while the first mentioned piston members begin to moveaway from their respective stop faces. The piston members thussuccessively operate the control turning movement of the cylinder memberas the eccentric rotates.

The piston members 15 are supported on the casing for oscillationbetween the stops 51a and 51b and are held against axial reciprocationby means of the piston mounting apparatus 16. This apparatusadvantageously includes a roller 61 disposed in each of the notches 51,with its axis paralleling the axis of the shaft. The roller engages theradially outer end of the respective one of the pistons 15 and limitsoutward movement of the piston member while permitting free oscillationof the piston member in a direction crosswise of its axis. The rollerhas rolling contact with the base of the notch 51 and the end of thepiston member and, when the piston member moves laterally a distanceequal to twice the eccentricity E of the eccentric, the roller only hasto move one-half this distance. Accordingly, the roller 61 is preferablyformed with outer diameter that exceeds the width of the piston by anamount equal to the eccentricity E. Stated otherwise, if the notch 51has a width equal to the circumferential width of the piston plus twicethe eccentricity, then the roller has an outer diameter which is lessthan the width of the notch by an amount equal to the eccentricity. Withthis arrangement, the roller 61 will also engage the stop faces 51a and51b at the time the respective piston engages the stop face.

In the embodiment illustrated, the pistons are small and displace only asmall amount of fluid during each reciprocation. In accordance with thepresent invention, the pistons are magnetically held to the casing toinhibit axial reciprocation of the pistons during oscillation of thecylinder member. Either the casing member 21 or the piston 15 or bothcan be magnetized. If only one is magnetized, the other will, of course,have to be formed of a ferromagnetic material. However, when employingthe rollers 61, it is preferable to at least magnetize the pistons tohold the pistons in contact with the rollers during lateral oscillationof the pistons with the cylinder member.

Since some of the pistons may tend to bind in the cylinder bores,particularly if the pump has not been in use for a while, a mechanicalmeans is also provided for preventing radial shifting movement of thepistons. For this purpose, the piston members are formed with a notch 64in the side thereof adjacent their outer ends and which notch definesinner and outer shoulders 64a and 641) (see FIG. 3). An annular ring 65is disposed around the inner periphery of the annular casing member 21and arranged to engage the outer shoulder 64a if the piston members tendto stick in the cylinder, to positively hold the piston members againstinward movemnt. As will be noted from FIG. 1, the piston member is freeto move circumferentially around the ring 65 between the stops 51a and51b during oscillation of the piston members.

As shown in FIGS. 1 and 5, the ring 65 is disposed in a groove 66 in theport plate 23 and engages the inner periphery of the annular casingmember 21. A similar ring 67 is disposed in a groove 68 in the portplate 22 and also engages the inner periphery of the casing member 21.The ring members 65 and 67 are thus radially supported on the portplates 23 and 22 and engage the casing member 21 to radially center thesame with respect to the port plates.

The cylinder member 12 is formed with a plurality of valve ports 81,each individual to one of the cylinders 37. In order to substantiallybalance the axial hydraulic forces on the cylinder, the valve ports 81are advantageously arranged to extend completely through the cylindermember and open at opposite sides thereof, as is clearly shown inFIG. 1. Each valve port 81 in the rotor is cooperable with a respectivepair of inlet and discharge ports in the casing to alternatelycommunicate the cylinder 3'7 with the inlet and discharge ports. Whilethe inlet and discharge ports could be located all in one or the otherof the port plates 22 and 23, it is preferable, when using a relativelylarge number of pump cylinders, to locate some of the ports in one ofthe plates and others of the ports in the other plate. As shown in FIG.4, a plurality of pairs of inlet and discharge ports 84 and 85,corresponding to one half the total number of inlet and discharge ports,are formed in the port plate 22 and alternate pairs of inlet anddischarge ports designated 84' and 85' are formed in the other portplate 23. The inlet ports 84 and 84 communicate through passages 86 and86' with distributor grooves 87 and 87' in the port plates 22 and 23respectively. Fluid under pressure is supplied to the distributorgrooves in any suitable manner.

However, in order to facilitate stacking of a plurality of pumping unitseach including a casing member 21, port plates 22 and 23, and shaft 14,it is preferable to provide inlet passage such as 88 and 88' in bothport plates 22 and 23, with the inlet passages arranged to open at theouter side of the port plates to communicate with the inlet passage inan adjacent pumping unit, when more than one unit is stacked together.As shown, the inlet passage 38 in one port plate is closed by the endplate 26 and the inlet passage in the other end plate 23 communicateswith an internally threaded opening an in the end member 27. When morethan one pumping unit is stacked together, the inlet passage 88 in oneunit will be positioned to communicate with the inlet passage 88' in theadjacent unit to enable supply of fluid to the several units from acommon inlet. As shown in FIG. 1, the shaft 14 is keyed at both ends forconnection. by a coupling such as 44 to the shaft of an adjacent unit.As will be seen from FIG. 5, fluid from one of the distributor grooves87' can flow around the outer periphcry of the cylinder member 12 andthrough the pump cavity 11 into the other distributor groove 87, tosupply fluid to the inlet ports 34 communicating with that groove. Theseveral outlet passages 85 in the port plate 22 are connected toindividual discharge passages 91a-9llf which passages open at end faces94 and 95 on the port plate 22. The individual outlet passages 85' andthe port plate 23 are similarly connected through individual outletpassages 92a-92f which open at opposite end face 94' and 95 on the portplate 23.

The inlet and discharge passages such as 84, 85; 84' and 85', of eachpair are angularly spaced apart relative to the axis of the shaft 14and, as best shown in FIG. 3, the valve ports 81 in the cylinder memberare movable in an orbital path, alternately into communication with theinlet and discharge ports. Thus, the eccentric produces a radialshifting movement of the cylinder member to effect reciprocation of thecylinder member relative to the pistons and cyclically vary the volumeof the displacement chambers in the cylinders. In addition, theeccentric produces an oscillation of the cylinder member in a directioncircumferentially of the shaft and crosswise of the axis of the pistons,and which oscillation is substantially 90 out of phase with thereciprocation of the pistons. This crosswise oscillation of the cylindermember effects movement of the valve port between the inlet anddischarge ports, and thus valves the flow of fluid to and from the pumpcylinders in proper timed relation with the reciprocation of thepistons.

The outlets of the several pump cylinders are thus connected toindividual discharge passages 91a91f and 9292f to provide separateproportional discharges, if desired. These individual discharges can beutilized separately, for example, in a fuel feed system for a multiplecylinder engine or in a lubrication system requiring multiple dividedflows. Two or more of the independent discharges from the pump can alsobe combined, if desired, and, as shown in FIG. 6, manifolds 101 and 102are attached to end faces 95 and 95', as by fasteners 103. The manifold101 has openings 104, 105 and 106 which are adapted to communicate withthe passages 91:1-91 and which openings are inter-connected by passages107 and 108 to combine the flows from the several passages. In theembodiment illustrated, the manifold 102 similarly has openings 111, 112and 113 adapted to register with the passages 92d92f. These openings arealso interconnected as by passages 115 and 116 to combine the flows fromthe several outlet passages 92d92f. Conveniently, the outlets from bothmanifolds can be combined by a cross pipe 118, which pipe is sealed tothe manifolds 101 and 102 as by O-rings 119 and intercommunicates thepassages in the same to combine the flows from both manifolds.Obviously, by suitable arrangement of the manifolds, any desiredcombination of flows can be achieved. As previously described, a numberof pumping units can be stacked to provide additional proportionalflows, if desired.

From the foregoing, it is thought that the operation and construction ofthe device will be readily understood. As the eccentric 13 rotates, thecylinder member is moved in orbital fashion in the pump cavity to effectcyclic reciprocation of the pistons in the cylinders. The piston membersare supported by the roller 61 and ring 65 on the casing in such amanner as to constrain the pistons against axial reciprocation whilepermitting oscillation of the pistons in a direction crosswise of theaxis of the pistons during orbital movement of the cylinder member. Thestop faces 51a and 51b are so arranged as to engage the ends of thepistons and control oscillation of the pistons. As the cylinder memberoscillates in a direction circumferentially of the shaft, the valve port81 moves alternately into communication with the inlet and dischargeports to valve the flow to and from the cylinders in proper timedrelation with the reciprocation of the pistons therein,

I claim:

1. A fluid pump or motor comprising, a pump casing defining a cavityhaving end wall means, an annular cylinder member in said cavity, ashaft extending into said cavity and having eccentric means rotatablyconnected to said cylinder member for moving the same in an orbitalpath, said cylinder member having a plurality of generally radiallyextending displacement chambers therein, a plurality of piston membersslidable in said displacement chambers and extending outwardly from saidcylinder member, means for constraining said piston members and saidcylinder member from turning with said eccentric means, said lastmentioned means including pockets on said easing into which the pistonmembers extend, each pocket defining a pair of stop faces to makecontact with each individual piston member and spaced apart in adirection circumferentially of said shaft a distance substantially equalto the width of the piston member measured in a directioncircumferentially of the shaft at the point of engagement with the stopfaces plus twice the eccentricity of Said eccentric means to alloW thepiston members and cylinder member to oscillate in a directioncircumferentially of the shaft as the eccentric means rotates, and meansfor valving the flows of fluid to and from said displacement chambers intimed relation with the reciprocation of the pistons in the displacementchambers.

2. A fluid pump or motor comprising, a pump casing defining a cavityhaving end wall means, an annular cylinder member in said cavity, ashaft extending into said cavity and having eccentric means rotatablyconnected to said cylinder member for moving the same in an orbitalpath, said cylinder member having a plurality of generally radiallyextending displacement chambers therein, a plurality of piston membersslidable in said displacement chambers and extending outwardly from saidcylinder member, means for constraining said piston members and saidcylinder member from turning with said eccentric means, said lastmentioned means including means of said casing defining pairs of stopfaces individual to each piston member and spaced apart in a directioncircumferentially of said shaft a distance substantially equal to thewidth of the piston member measured in a direction circumferentially ofthe shaft at the point of engagement with the stop faces plus twice theeccentricity of said eccentric means to allow the piston members andcylinder member to oscillate in a direction circumferentially of theshaft as the eccentric means rotates, a roller disposed between eachpair of stop faces and engaging the radially outer end of the pistonmember to radially support the piston members against outward movement,and means for valving the flows of fluid to and from said displacementchambers in timed relation with the reciprocation of the piston membersin the displacement chambers, said rollers having a diameter which isless than the spacing between the respective pair of stop faces by anamount substantially equal to the eccentricity of said eccentric means.

3. A fluid pump or motor comprising, a pump casing including an annularcasing member having an inner peripheral wall and end walls at oppositeends of the annular casing member defining a cavity, an annular cylindermember in said cavity, a shaft extending into said cavity and havingeccentric means rotatably connected to said cylinder member for movingthe same in an orbital path, said cylinder member having a plurality ofgenerally radially extending displacement chambers therein, a pluralityof piston members slidable in said. displacement chambers and extendingoutwardly from said cylinder member, said peripheral wall having aplurality of inwardly opening recesses into which the piston membersextend to constrain said piston members and said cylinder member fromturning with said eccentric means, said recesses each defining a pair ofstop faces to make contact with each individual piston member and spacedapart in a direction circumferentially of said shaft a distancesubstantially equal to the width of said piston members plus twice theeccentricity of said eccentric means to allow the piston members andcylinder member to oscillate in a direction circumferentially of theshaft as the eccentric means rotates, means for limiting axialreciprocation of said piston members while permitting oscillating ofsaid piston members in a direction circumferentially of said shaft, andmeans for valving the flows of fluid to and from said displacementchambers in timed relation with the reciprocation of said piston membersin the displacement chambers.

4. A fluid pump or motor comprising, a pump casing defining a cavityhaving end wall means, an annular cylinder member in said cavity, ashaft extending into said cavity and having eccentric means rotatablyconnected to said cylinder member for moving the same in an orbitalpath, said cylinder member having a plurality of generally radiallyextending displacement chambers therein arranged in sets of four withthe chambers of each set angularly spaced apart from each other, aplurality of piston members slidable in said displacement chambers andextending outwardly from said cylinder member, means for constrainingsaid piston members and said cylinder member from turning with saideccentric means, said last mentioned means including pockets on saideasing into which the piston members extend, each pocket defining a pairof stop faces to make contact with each individual piston member andspaced apart in a direction circumferentially of said shaft a distancesubstantially equal to the width of the piston member measured in adirection circumferentially 0f the shaft at the point of engagement withthe stop faces plus twice the eccentricity of said eccentric means toallow the piston members and cylinder member to oscillate in a directioncircumferentially of the shaft as the eccentric means rotates, said endwall means on said casing having a plurality of inlet and dischargeports arranged in pairs individual to each displacement chamber, saidinlet and discharge ports of each pair being angularly spaced apartrelative to the axis of said shaft a valve port in said cylinder memberindividual to each displacement chamber and communicating therewith,said valve ports being movable alternately into communication With theinlet and discharge ports of the respective pair as said cylinder memberoscillates in a direction circumferentially of said shaft.

5. A fluid pump or motor comprising, a pump casing including an annularcasing member having an inner peripheral wall and end walls at oppositeends of the annular casing member defining a cavity, an annular cylindermember in said cavity, a shaft extending into said cavity and havingeccentric means rotatably connected to said cylinder member for movingthe same in an orbital path, said cylinder member having a plurality ofgenerally radially extending displacement chambers therein, a pluralityof piston members slidable in said displacement chambers and extendingoutwardly from said cylinder member, said peripheral wall having aplurality of inwardly opening recesses each for receiving the ends of arespective one of the piston members to constrain said piston membersand said cylinder member from turning with said eccentric means, saidrecesses defining pairs of stop faces individual to each piston memberand spaced apart in a direction circumferentially of said shaft adistance substantially equal to the width of said piston members plustwice the eccentricity of said eccentric means to allow the pistonmembers and cylinder member to oscillate in a directioncircumferentially of the shaft as the eccentric means rotates, means forlimiting axial reciprocation of said piston members while permittingoscillating of said piston members in a direction circumferentially ofsaid shaft, and means for valving the flows of fluid to and from saiddisplacement chambers in timed relation with the reciprocation of saidpiston members in the displacement chambers and a roller disposedbetween each pair of stop faces and engaging the radially outer end ofthe piston member to radially support the piston member against outwardmovement, said rollers having a diameter less than the width of saidrecesses by an amount substantially equal to the eccentricity of saideccentric means.

6. A fluid pump or motor comprising, a pump casing defining a cavityhaving end Wall means, an annular cylinder member in said cavity, ashaft extending into said cavity and having eccentric means rotatablyconnected to said cylinder member for moving the same in an orbitalpath, said cylinder member having a plurality of generally radiallyextending displacement chambers therein arranged in sets of four withthe chambers of each set angularly spaced apart 90 from each other, aplurality of piston members slidable in said displacement chambers andextending outwardly from said cylinder member, means for constrainingsaid piston members and said cylinder member from turning with saideccentric means, said last mentioned means including means on saidcasing defining pairs of stop faces individual to each piston member andspaced apart in a direction circumferentially of said shaft a distancesubstantially equal to the width of the piston member measured in adirection circumferentially of the shaft at the point of engagement withthe stop faces plus twice the eccentricity of said eccentric means toallow the piston members and cylinder member to oscillate in a directioncircumferentially of the shaft as the eccentric means rotates, said endwall means on said casing having a plurality of inlet and dischargeports arranged in pairs individual to each displacement chamber, saidinlet and discharge ports of each pair being angularly spaced apart 8relative to the axis of said shaft, a valve port in said cylinder memberindividual to each displacement chamber and communicating therewith,said valve ports being movable alternately into communication with theinlet and diS- charge ports of the respective pair as said cylindermember oscillates in a direction circumferentially of said shaft, and aroller disposed between each pair of stop faces and engaging theradially outer end of each piston member, said rollers having an outerdiameter less than the spacing between said stop faces by an amountsubstantially equal to the eccentricity of said eccentric means.

7. The combination of claim 6 wherein at least one, the pump casing orthe piston members, are magnetized to magnetically hold the pistonmembers against the rollers and the rollers against the casing toconstrain the piston members against axial reciprocation.

8. The combination of claim 6 wherein said piston members have a notchin the side thereof, and means on said casing extending into said notchand engaging the piston members to limit movement of the piston membersin a direction axially thereof while permitting limited oscillation ofthe piston members in a direction crosswise of their axes.

9. A fluid pump or motor comprising, a pump casing including an annularcasing member having an inner peripheral wall and end walls at oppositeends of the annular casing member defining a cavity, an annular cylindermember in said cavity, a shaft extending into said cavity and havingeccentric means r-otatably connected to said cylinder member for movingthe same in an orbital path, said cylinder member having a plurality ofgenerally radially extending displacement chambers therein, a pluralityof piston members slidable in said displacement chambers and extendingoutwardly from said cylinder member, said peripheral wall having aplurality of inwardly opening recesses into which the end of arespective one of the piston members extends to constrain said pistonmembers and said cylinder member from turning with said eccentric means,each recess defining a pair of stop faces to make contact with eachindividual piston member and spaced apart in a directioncircumferentially of said shaft a distance substantially equal to thewidth of said piston members plus twice the eccentricity of saideccentric means to allow the piston members and cylinder member tooscillate in a direction circumferentially of the shaft as the eccentricmeans rotates, means for limiting axial reciprocation of said pistonmembers while permitting oscillating of said piston members in adirection circumferentially of said shaft, and means for valving theflows of fluid to and from said displacement chambers in timed relationwith the reciprocation of said piston members in the displacementchambers, said means for limiting axial reciprocation of said pistonmembers comprising a shoulder on each piston member and an annular ringon the casing concentric with said shaft and engaging said shoulders oneach of the piston members, said ring being radially anchored in one ofsaid end walls and engaging said peripheral wall of said casing memberto radially locate the casing member.

References Cited by the Examiner UNITED STATES PATENTS 2,173,432 9/39Benedek 103-161 3,016,019 1/62 Rineer 103-121 FOREIGN PATENTS 869,1543/53 Germany. 321,313 11/29 Great Britain.

LAURENCE V. EFNER, Primary Examiner.

1. A FLUID PUMP OR MOTOR COMPRISING, A PUMP CASING DEFINING A CAVITYHAVING END WALL MEANS, AN ANNULAR CYLINDER MEMBER IN SAID CAVITY, ASHAFT EXTENDING INTO SAID CAVITY AND HAVING ECCENTRIC MEANS ROTATABLYCONNECTED TO SAID CYLINDER MEMBER FOR MOVING THE SAME IN AN ORBITALPATH, SAID CYLINDER MEMBER HAVING A PLURALITY OF GENERALLY RADIALLYEXTENDING DISPLACEMENT CHAMBERS THEREIN, A PLURALITY OF PISTON MEMBERSSLIDABLE IN SAID DISPLACEMENT CHAMBERS AND EXTENDING OUTWARDLY FROM SAIDCYLINDER MEMBER, MEANS FOR CONSTRAINING SAID PISTON MEMBERS AND SAIDCYLINDER MEMBER FROM TURNING WITH SAID ECCENTRIC MEANS, SAID LASTMENTIONED MEANS INCLUDING POCKETS ON SAID CASING INTO WHICH THE PISTONMEMBERS EXTEND, EACH POCKET DEFINING A PAIR OF STOP FACES TO MAKECONTACT WITH EACH INDIVIDUAL PISTON MEMBER AND SPACED APART IN ADIRECTION CIRCUMFERENTIALLY OF SAID SHAFT A DISTANCE SUBSTANTIALLY EQUALTO THE WIDTH OF THE PISTON MEMBER MEASURED IN A DIRECTIONCIRCUMFERENTIALLY OF THE SHAFT AT THE POINT OF ENGAGEMENT WITH THE STOPFACES PLUS TWICE THE ECCENTRICITY OF SAID ECCENTRIC MEANS TO ALLOW THEPISTON MEMBERS AND CYLINDER MEMBER TO OSCILLATE IN A DIRECTIONCIRCUMFERENTIALLY OF THE SHAFT AS THE ECCENTRIC MEANS ROTATES, AND MEANSFOR VALVING THE FLOWS OF FLUID TO AND FROM SAID DISPLACEMENT CHAMBERS INTIMED RELATION WITH THE RECIPROCATION OF THE PISTON IN THE DISPLACEMENTCHAMBERS.